Some babies are just slower to develop in certain areas. This is the time when the bones ossify and muscles really start to develop their strength. Depending on how much fluid you have around your baby and depending on where they are actually "hitting" you, they may not be able to really reach anything where you would actually feel the contact with any intensity.
Or, like my first child, they could be very docile. I don't remember getting very much movement with her until around 10 at night when she would get the hiccups.
Other than that, she was happy to be quiet and still... so unlike her today!